Glass fiber friction element

ABSTRACT

A friction material, such as a clutch facing, formed of continuous bundle of parallel continuous glass fibers spirally or randomly wound upon themselves in the form of an annular disc impregnated with heat curable cement and having brass wires helically disposed around the bundles.

United States Patent 1191 111 3,743,069 Barnett et al. July 3, 1973 [54]GLASS FIBER FRICTION ELEMENT 2,749,266 6/1956 Eldred 192/107 M 2, 24, Ill I955 [75] Inventors: Irvin Barnett, Martmsvrlle; Walter 1 2; $1964Lombardy a| U 92/107 M B. Peters, South Orange, both 0f NJ. 3 0 131 1219 2 [73] Assignee: Johns-Manville Corporation, New 3'600258 8/ I97192/107 M York, NY FOREIGN PATENTS OR APPLICATIONS [22] Filed: June 24,1971 854,005 1/1940 France 192/107 M [21] Appl' l564l0 PrimaryExaminer-Benjamin W. Wyche Attorney-John A. McKinney, Robert M. Kroneand [52] US. Cl. 192/107 M, 156/173, 161/47, Joseph J. Kelly et al.

188/218 XL, l61/DlG. 4 [51] Int. Cl. F16d 13/60 [57] ABSTRACT [58] i'g 7fK g 'i'M 27 5? A friction material, such as a clutch facing. formed of47 DIG continuous bundle of parallel continuous glass fibers spirally orrandomly wound upon themselves in the form of an annular discimpregnated with heat curable [56] References C'ted cement and havingbrass wires -helically disposed UNITED STATES PATENTS around the bundles3,526,306 9/1970 Bentz et al. 192/107 M 18 Claims, 6 Draw ng F gurePATENIEDJUL3 1915 3.743 069 sum 1 or 2 I ALLOY-nay GLASS FIBER FRICTIONELEMENT CROSS REFERENCE TO RELATED APPLICATIONS This invention isconcerned with a friction element formed by continuous bundle ofcontinuous and parallel glass filaments. The bundle and the process ofmanufacture are disclosed in copending application Ser. No. 156,267 ofWalter B. Peters and Irvin Barnett filed June 24, 197 l-, and alsoassigned to Johns-Manville Corporation.

BACKGROUND OF THE INVENTION This invention relates to friction elements,particularly clutch facings, formed of continuous bundles of continuousglass fibers, helically wrapped by brass wires and impregnated with aheat curable cement and spirally or randomly wound upon themselves inthe form of an annular disc.

The prior art contains many showings of asbestos fibers in clutch andfriction material. Asbestos fibers contain many of the basiccharacteristics desirable for use in friction materials, for example:

1. Wetability for adhesion to binder matrix.

2. High tensile strength.

3. Good friction material because:

a. Heat stable b. Hardness range generally below that of steel,therefore, will not wear metal friction facings.

c. Desirable coefficient of friction,

d. Fine fibrils on asbestos fibers that stabilize and reinforce thematrix.

Asbestos fibers combined with cotton fibers (or synthetic fibers) withappropriate cement have proven to be a good friction material foraverage service. Brass wires or metal particles have long been used inthe friction material, primarily to dissipate heat. The formulas forclutch and brake materials including cements are numerous in varyingcombinations. As demands for greater spin strengths (resistance tocentrifugal forces) increased, various arrangements have been proposed.These include metal backing plates to which the actual friction materialis bonded. Backing plates have also been formed of laminated glass clothwith asbestos and other fibers and cement as the friction material. Theglass fibers were present primarily for strength and not as the frictionmaterial.

As spin strength requirements became more demanding, glass fibers beganto appear in the prior art. U.S. Pat. No. 3,270,846 (filed 1957)discloses use of up to 27 percent glass fibers in combination with othermaterials to form a friction facing for use in wet clutches which run inoil or other fluids. The specification does not clearly teach in whatmanner these fibers are incorporated with the other materials, which ofcourse, include asbestos fibers. Prior thereto, U.S. Pat. No. 3,068,131(filed 1958) had disclosed the use of plies of flat woven spun glassfabric in the reinforcing ring for supporting clutch facing material ofasbestos fiber yarn and resin. U.S. Pat. No. 3,365,041 (filed 1965)discloses a reinforcing ring 11 of glass cloth and cement sandwichedbetween rings of friction elements com-' prised of 75 percent asbestosfibers plus other material (not glass) and cement. Note that glass isfor spin strength and other reinforcement while asbestos fibers andbrass wires are for frictional engagement. U.S. Pat. No. 3,429,766(filed 1965) discloses the use ofa clutch facing of spirally woundmultiply strips of asbestos fibers, metallic wire and cement reinforcedby woven glass fabric By an inspection of FIG. 3, it is apparent thatonly one layer in five is glass cloth. The specification reveals thatthe glass fibers are for reinforcement, though it would appear that afew would likely be in friction contact. Again asbestos is by-and-largethe friction fiber. In a later U.S. Pat. No. 3,526,306 (filed 1968)glass fibers 13 are used in the apex of the chevron for reinforcementand away from the wear surface.

The specification indicates that fabric 11 can be made of asbestosfibers alone or mixtures with other fibers such as cotton, wool, rayon,linen or jute. Fine metal wires 12 are used with fabric 11. Againasbestos fibers provides the main friction fiber.

The prior art has taught the use of asbestos fibers for frictionalcontact and glass fibers for strengthening the facing. Asbestos has beenknown to have the desirable characteristics as mentioned previously inthis specification. It appears that the superiority of asbestos fibersin friction material has never been challenged even though, as the priorart clearly shows, it has been necessary to provide reinforcement ofglass fibers.

Applicants discovery is that glass fibers (with brass wire and cement)provide an improved friction surface with superior characteristicsparticularly in spin strength.

In the use of asbestos fibers for clutch facing material, it isconventional to twist relatively short (i.e., staple) asbestos fiberswith nonferrous wire such as copper, brass or zinc together andimpregnate the twisted strand with a friction cement. The wiresprimarily serve as a carrier for relatively short asbestos fibers duringprocessing, though they provide some friction and define means forfrictional heat transfer and dissipation when formed into a frictionfacing. The asbestos fibers generally fall within a random patternintertwisted with the wire. The wires meander throughout the clutchfacing, but follow a generally spiral path.

According to the present invention, continuous glass fibers which havebeen processed into continuous bundle are spirally or randomly wrappedupon themselves into disc-like form and cured under elevated heat andpressure. The cured form may then be machined and drilled to define afriction product, such as a clutch facmg.

BRIEF SUMMARY OF THE INVENTION It is an object of this invention toprovide a friction material formed of continuous glass filaments andcement.

It is another object of this invention to provide a friction materialsuch as a clutch facing comprised of parallel continuous glass filamentsimpregnated with cement and spirally or randomly wound upon themselvesinto a disc-like form and cured under elevated temperature and pressure.

It is a still further object of this invention to provide a continuousbundle of continuous and parallel glass filaments, impregnated by cementand helically wrapped by filament means, spirally or randomly wound uponitself into a disc-like form and cured under elevated temperature andpressure.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fullyunderstood and further objects and advantages thereof will becomeapparent when reference is made to the following detailed description ofthe preferred embodiment of the invention and the accompanying drawingin which:

FIG. 1 illustrates a short portion of a bundle of continuous andgenerally parallel glass filaments;

FIG. 2 represents a continuous bundle being drawn from a spool andspirally wound upon itself into disclike form;

FIG. 3 is an elevation or face view of a friction member, such as aclutch facing in accordance with the invention;

FIG. 4 is a side or edge view of the material shown in FIG. 3; and

FIG. 5 is a fragmentary enlarged sectional view taken generally alongline 55 of FIG. 3; and

FIG. 6 represents a continuous bundle being drawn from a spool andrandomly wound upon itself into disclike form.

DESCRIPTION OF THE PREFERRED EMBODIMENT In referring to the drawings,the reference numeral 10 indicates an annularly shaped disc-likefriction material such as a clutch facing. The invention herein, whileprimarily relating to a clutch facing, has use as a friction materialsuch as in disc brakes.

The clutch facing material defined herein is formed by wrappingcontinuous bundle 12 of generally parallel continuous ECK glassfilaments spirally or randomly upon themselves to a disc-like preformand cured under elevated temperature and pressure. Continuous bundle l2and the process by which it is prepared is fully disclosed in copendingUS. Pat. application Ser. No. 156,267 filed concurrently herewith.Briefly, that disclosure relates to collection into a continuous bundlenumerous continuous glass filaments having diameters in the range of 12to 14 microns. At one stage of processing they are impregnated with acement composition. Thereafter they are partially dried and helicallywrapped by filament means 16, such as brass wires, to hold the bundletogether throughout its continuous length. It has been found that about200 to 800 continuous K filaments can first be collected parallel toeach other to define a strand. Then some 10 to 120 strands are furthercollected parallel to each other to define a roving. From 6 to 8 rovingsare brought together parallel to each other after having beenimpregnated with cement and retained in a bundle by having a pluralityof brass wires helically applied around their collected periphery.

The following cement composition was used to impregnate glass rovings:Rubber 30-40 percent; Accelerate and Curing Agents, such as DOTG -30percent; Resin l5-30 percent; and Filler 20-30 percent. After thecontinuous filaments, whether in strand or roving form, are impregnatedwith cement, they are at least partially dried by exposure to steam orair to carry away the volatile hydrocarbons.

Continuous bundle 12, after being helically wrapped, is stored on spoolsor drums in lengths of several hundred to over 1000 feet for subsequentuse. FIG. 2 illustrates schematically the process by which continuousbundle I2 is supplied from a spool 18 and spirally wound onto arevolving mandrel mold 20. This preform comprises a pair of plates 22mounted on a rotatable shaft 24. The plates are axially spaced apart aselective distance equal to the desired thickness of the disc-likepreform. Continuous bundle 12 is started around shaft 24 and slowlyspirally wound in spiral where the length keeps building up on itself inever increasing radii. Alternatively, the bundles may be applied byrandom winding wherein the bundles are constantly varying in theinstantaneous radius at which they are being wound, as illustrated inFIG. 6.

The uncured spirally or randomly wound disc-like preform material isremoved from mandrel 20. It maintains itself in a disc-like form by thefriction between adjacent and overlapping bundle portions resulting fromthe winding operation. The inherent tackiness of the uncured cementcomposition also helps to hold the bundle in position. The uncuredpreform is then placed between flat platens under pressure in the rangeof 2000 to 2500 psi and cured at a temperature of from 320 to 340F for 4minutes. This initial cure hardens resins to a nonflow condition.Thereafter, the partially cured and densified preforms are removed andsubjected to a post bake for completing the polymerization of theresins. The post bake comprises further curing under reduced pressurefor about 6 hours at 350F and 2 hours at 400F. Upon completion of thispost cure, the disc is ready to have flashing removed and be ground tothe proper thickness. The finished facings are provided with rivet holes14 having counterbores for reception of attaching rivets for securingthe facings to a clutch plate or brake mounting, not shown.

Bundle 12 in the state shown in FIGS. 1, 2 and 6, impregnated withcement and wrapped with brass wires, comprises by weight ECK glassfilaments in the range of 45 to 50 percent; cement in the range of 47-51percent, and brass wire from 3-4 percent. As indicated, volatilehydrocarbons have been expelled from the cement prior to having helicalwrappings of brass wire applied therearound. In such a state thecontinuous bundle is bendable and pliable so that it can be easily woundupon mandrel 20. The parallel glass filaments in the bundle are adaptedto follow the desired contour and be wound over each other to generallyfill all the spaces in the preform 20. The brass filament windings,since they extend around the outer periphery of the glass filament inbundle 12, are exposed to either face of the friction material. Eachfilament that is exposed to the surface also extends deep within thefacing material since it encircles the bundle. They serve to hold thebundle and transmit heat. FIG. 5, which is an enlarged sectional viewtaken generally along line 5- 5 of FIG. 3, shows the bundles made up of6 to 8 rovings which have been built up spirally one on another. Theindividual filaments continue to lie generally parallel to each other asthey did in the roving or strand stage. As the bundle is spirally orrandomly wound to define the body of the preform, the fibers areoriented to lie generally arcuately at a general radius from the center.The wear or friction surface of the clutch facing includes glassfilaments with their sides generally present for frictional contact witha flywheel.

Continuous glass fibers, with sides exposed to friction contact, providea clutch facing having equal to superior performance when compared toasbestos fibers, and a marked superiority in spin strength. A number oftests have been run on clutch facings of identical size and the resultsof these tests are tabulated as follows:

Glass (3) Astestos (2) 10,167 13,000 9,950 13,275 9,066 13,300 8,93313,033 8,650 13,250 9,258 12,614 Average 8,280 9,750

9,069 Average l. 500F; size 10.4 inches X6.5 inches x 0.0l35 inchesthick. 2. Short length asbestos fibers intertwisted with brass wire. 3.Glass fibers in continuous bundles helically wrapped with brass wire. 4.Each figure represents average of six specimens.

It may be desired to compare the above tests with the tabular resultspresented in Bentz, U.S. Pat. Nos. 3,520,390 and 3,526,306.

It will be seen that substantial burst strength is provided by clutchfacings formed by spirally wrapping continuous glass filaments uponthemselves in the manner disclosed and claimed herein. Clutch facingsusing glass fibers have equal or better wear, face and torquetransmittal characteristics to define a commercially superior frictionmaterial.

It will be understood that various changes may be made without departingfrom the spirit of the invention which is defined in the followingclaims. 1

We claim: 1. A friction facing consisting essentially of: an annularflat body formed of a generally spirally wound continuous bundle ofcontinuous longitudinally coextensive generally parallel glass fibers,

said bundle impregnated with a heat curable cement composition,

filament means helically encircling portions of the periphery of thecontinuous bundle substantially throughout its length for retaining theglass fibers.

2. The invention according to claim 1 wherein the filament means is heatconductive.

3. The invention according to claim 2 wherein the filament means ismetallic.

4. The invention according to claim 3 wherein the filament means isnonferrous.

5. The invention according to claim 4 wherein the filament means isbrass wire.

6. A friction facing consisting essentially of:

an annular disc-like body formed ofa spirally wound continuous bundle,

said bundle comprising numerous longitudinally coextensive generallyparallel continuous glass fibers impregnated with a heat curable cementand having heat conductive metallic filament means helically appliedabout the bundle,

said filament means including portions lying adjacent a frictionengaging surface of the facing and also including portions running todeep within the facing body for conducting frictional heat thereinto fordissipation.

7. The invention according to claim 6 wherein the filament means isbrass wire.

8. A clutch facing consisting essentiallyof:

a disc-like body formed ofa continuous bundle of numerous longitudinallycoextensive generally parallel continuous glass fibers spirally woundupon itself in the plane of the body,

said bundle of glass fibers being impregnated with a heat curablecement,

said bundle throughout its spiral arrangement having heat conductivefilament means helically disposed thereabout,

said helically disposed filament means having portions adapted forexposure to a friction face for absorbing frictional heat and beingcontinuous with portions extending deep into the body for dissipation ofheat thereinto.

9. The invention according to claim 8 wherein the heat conductivefilament is brass.

10. A friction facing consisting essentially of:

an annular flat body formed of a generally randomly wound continuousbundle of continuous longitudinally coextensive generally parallel glassfibers,

said bundle impregnated with a heat curable cement composition,

filament means helically encircling portions of the periphery of thecontinuous bundle substantially throughout its length for retaining theglass fibers.

11. The invention according to claim 10 wherein the filament means isheat conductive.

12. The invention according to claim 11 wherein the filament means ismetallic.

13. The invention according to claim 12 wherein the filament means isnonferrous.

14. The invention according to claim 13 wherein the filament means isbrass wire.

15. A friction facing consisting essentially of:

an annular disc-like body formed of a randomly wound continuous bundle,

said bundle comprising numerous longitudinally coextensive generallyparallel continuous glass fibers impregnated with a heat curable cementand having heat conductive metallic filament means helically appliedabout the bundle,

said filament means including portions lying adjacent a frictionengaging surface of the facing and also including portions running todeep within the facing body for conducting frictional heat thereinto fordissipation.

16. The invention according to claim 15 wherein the filament means isbrass wire.

17. A clutch facing consisting essentially of:

a disc-like body formed of a continuous bundle of numerouslongitudinally coextensive generally parallel continuous glass fibersrandomly wound upon itself in the plane of the body,

said bundle of glass fibers being impregnated with a heat curablecement,

said bundle throughout its random arrangement having heat conductivefilament means helically disposed thereabout,

said helically disposed filament means having portions adapted forexposure to a friction face for absorbing frictional heat and beingcontinuous with portions extending deep into the body for dissipation ofheat thereinto.

18. The invention according to claim 17 wherein the heat conductivefilament is brass.

gg gg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,743,069 Dated July 3,' 1973 Inventor(s) Irvin Barnett and Walter B.Peters.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 29, after "facings" delete and insert Column 5, line 18,"0.0135" should be -'-.l35--.

Signed and sealed this 26th day of March 1974.

(SEAL) Attest:

'EDWARD M.FLETCHER,JR. C. MARSHALL DANN Attesting Officer Commissionerof Patents

2. The invention according to claim 1 wherein the filament means is heatconductive.
 3. The invention according to claim 2 wherein the filamentmeans is metallic.
 4. The invention according to claim 3 wherein thefilament means is nonferrous.
 5. The invention according to claim 4wherein the filament means is brass wire.
 6. A friction facingconsisting essentially of: an annular disc-like body formed of aspirally wound continuous bundle, said bundle comprising numerouslongitudinally coextensive generally parallel continuous glass fibersimpregnated with a heat curable cement and having heat conductivemetallic filament means helically applied about the bundle, saidfilament means including portions lying adjacent a friction engagingsurface of the facing and also including portions running to deep withinthe facing body for conducting frictional heat thereinto fordissipation.
 7. The invention according to claim 6 wherein the filamentmeans is brass wire.
 8. A clutch facing consisting essentially of: adisc-like body formed of a continuous bundle of numerous longitudinallycoextensive generally parallel continuous glass fibers spirally woundupon itself in the plane of the body, said bundle of glass fibers beingimpregnated with a heat curable cement, said bundle throughout itsspiral arrangement having heat conductive filament means helicallydisposed thereabout, said helically disposed filament means havingportions adapted for exposure to a friction face for absorbingfrictional heat and being continuous with portions extending deep intothe body for dissipation of heat thereinto.
 9. The invention accordingto claim 8 wherein the heat conductive filament is brass.
 10. A frictionfacing consisting essentially of: an annular flat body formed of agenerally randomly wound continuous bundle of continuous longitudinallycoextensive generally parallel glass fibers, said bundle impregnatedwith a heat curable cement composition, filament means helicallyencircling portions of the periphery of the continuous bundlesubstantially throughout its length for retaining the glass fibers. 11.The invention according to claim 10 wherein the filament means is heatconductive.
 12. The invention according to claim 11 wherein the filamentmeans is metallic.
 13. The invention according to claim 12 wherein thefilament means is nonferrous.
 14. The invention according to claim 13wherein the filament means is brass wire.
 15. A friction facingconsisting essentially of: an annular disc-like body formed of arandomly wound continuous bundle, said bundle comprising numerouslongitudinally coextensive generally parallel continuous glass fibersimpregnated with a heat curable cement and having heat conductivemetallic filament means helically applied about the bundle, saidfilament means including portions lying adjacent a friction engagingsurface of the facing and also including portions running to deep withinthe facing body for conducting frictional heaT thereinto fordissipation.
 16. The invention according to claim 15 wherein thefilament means is brass wire.
 17. A clutch facing consisting essentiallyof: a disc-like body formed of a continuous bundle of numerouslongitudinally coextensive generally parallel continuous glass fibersrandomly wound upon itself in the plane of the body, said bundle ofglass fibers being impregnated with a heat curable cement, said bundlethroughout its random arrangement having heat conductive filament meanshelically disposed thereabout, said helically disposed filament meanshaving portions adapted for exposure to a friction face for absorbingfrictional heat and being continuous with portions extending deep intothe body for dissipation of heat thereinto.
 18. The invention accordingto claim 17 wherein the heat conductive filament is brass.